In AIDS patients, the incidence of Pneumocystis carinii pneumonia (PCP) is increasing primarily due to the fact that the actual numbers of AIDS patients is increasing dramatically in the United States. Because of this, there is a need to develop faster and less time-consuming diagnostic techniques. The purpose of this study is to improve the sensitivity of sputum induction as a noninvasive diagnostic procedure in patients with suspected PCP. Patients undergo sputum induction using an ultrasonic nebulizer with a 3% saline solution. Specimens are processed by the microbiology department and are stained conventionally. In addition, an experimental human monoclonal immunofluorescent staining technique to determine the presence of pneumocystis in sputum is also being investigated. Those with "negative" sputums undergo bronchoscopy with bronchoalveolar lavage and transbronchial biopsy in order to determine an etiology for their pulmonary dysfunction and also to establish the sensitivity of sputum induction for the diagnosis of PCP. Preliminary data indicate a 90% sensitivity for the diagnosis of PCP by sputum induction. This technique may reduce the time, cost, and morbidity associated with establishing the diagnosis the diagnosis of PCP. This study has already resulted in publication in the New England Journal of Medicine and Annals of Internal Medicine. The study is being continued in order to improve the efficacy and cost of these techniques, in order to evaluate commercial products licensed by NIH on the basis of our monoclonal antibody, and in order to assess new technologies like polymerase chain reaction and nucleicacid probes.